The 59023300 is the Pentair FNS Plus Complete Grid Assembly for the 60 Sq Ft FNSP60 Filter. The complete grid assembly contains all of the internal components of the filter including Tie-Rod, Top Manifold, Spider Grid Locator, Spacer, and all of the grids. The complete grid assembly comes completely assembled and ready to be installed. This will only work with the FNS Plus model.